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July 2009 Archives

New spider mite fact sheet

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By Ken Ostlie and Bruce Potter

Reports of spider mite infestations continue from both soybean and corn, particularly from areas with prolonged drought.  Even if you've received rain recently, check for mite activity along field edges to determine if you've got a building problem.  You may need to factor spider mites into a soybean aphid spray decision.

The article is available on the web at:

Well so much for the relatively arthropod pest- free growing season.

by Dr. Ian MacRae, U of MN Extension Entomologist

There has been increasing pressure to apply insecticide and tank mixed pesticides at lower thresholds based on claims of increased yield benefits. While increased commodity prices can stimulate the desire to decrease risk tolerance and increase the use of pesticides, this is not always a paying proposition.

by Dr. Ian MacRae, U of MN Extension Entomologist


.... Low populations of Soybean Aphid (SBA) have been reported throughout NW MN and NE ND. Populations are still low and generally not on more than 30% of the plants. The cooler weather will slow reproduction for a few days but it is predicted to warm up by the weekend, at which time we'll start to see some more population growth and dispersal across fields. Although most fields are well below treatment levels so far, it is time to start scouting the soybean fields, getting a handle on what populations you may have and tracking progress and population growth.

2009 Soybean Cyst Nematode Survey in the Red River Valley

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by Dr. Charla Hollingsworth, U of MN Extension Plant Pathologist

In 1954, the first detection of the soybean cyst nematode (SCN) occurred in North Carolina. Since that time, the nematode has become the most important disease issue of soybean in the world. Spread with soil, this microscopic roundworm continues to gain ground in Minnesota soybean-producing areas. Essentially anything that can move small particles of soil will also transport this nematode.

Final Words of Caution on Wheat Midge

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by Phillip Glogoza, Extension Educator - Crops

A lot of wheat is now heading in NW Minnesota. In the northern most counties, degree day accumulations are just reaching the 1300 DD mark (see map), the point where 10% of female midge have emerged. Emergence will continue through 1600+ DD (90% female emergence).

Sunflower Rust is Widespread but Developing Slowly

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by Dr. Charla Hollingsworth, U of MN Extension Plant Pathologist

SNFLWR_Rust_pycnia.jpg Early lifecycle stage structures (pycnia) of sunflower rust were detected on volunteer sunflowers during early-June in Minnesota and North Dakota (Figure 1). These detections created concern because that meant:

  • the fungus was only two spore stages away from producing the spores responsible for epidemics (pycnia → aeciospores → urediospores);

  • it was much too early in the growing season to see rust developing; and

  • the fungus had overwintered in our agroecosystem in its sexual stage. A possible outcome of winter survival is the potential for genetic recombination by the pathogen where more virulence might occur on sunflower varieties grown here.
  • by Dr. Charla Hollingsworth, U of MN Extension Plant Pathologist

    Crop growth stages of spring wheat are rapidly approaching early flower in some locations. This is the time of year that managers must make a decision to apply a fungicide application targeted for Fusarium head blight (FHB) management.

    Northwest Research and Outreach Center - Crookston

    Crops and Soils Day

    Friday, July 17, 2009 8:00 A.M.

    By Lizabeth Stahl

    Hear the latest University of Minnesota research and information on strip tillage and compare strip-tillage equipment in action through field demonstrations at the 2009 "Minnesota Strip Till Expo" on Tuesday, August 11th, at the Southwest Research and Outreach Center in Lamberton.  This event will run, rain or shine, from 9:00 to 4:00, with registration starting at 8:30.  Entry to the Expo is free with lunch and refreshments available on the grounds for a fee.     

    By David Nicolai


    2009 U of M Field School for Ag Professionals Registration is open. Register by July 7th in order to receive a discount

    Online registration is available for the 2009 Field School for Ag Professionals to be held on July 15 - 16. The University of Minnesota Northwest Research and Outreach Center in Crookston will be the host site for the Field School. Participants may choose to attend either day or both days of the field school. The first day's program on July 15 will consist of four disciplines - weed science, soil science, entomology, and a crop diagnostics session. Students will attend each of these 1.5 hour hands-on sessions. Certified Crop Advisor CEUs in the areas of Soil & Water, Pest Management, and Crop Management will be offered. Instructors will include University of Minnesota State Extension Specialists and Regional Extension Educators.

    Weed Control in Roundup Ready Sugarbeet

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    by Dr. Jeff Stachler, Sugar beet Weed Scientist
    U of MN Extension / NDSU Extension

    For those growers unable to apply glyphosate to Roundup Ready sugarbeet for the first time due to wet soil conditions, apply the maximum rate of glyphosate allowed. The maximum glyphosate rate for Roundup Ready sugarbeet is 1.125 pounds acid equivalent per acre (lbs ae/A). This equates to 32 fluid ounces per acre (fl oz/A) of Roundup-branded products, 48 fl oz/A of 3.0 pounds acid equivalent per gallon (lbs ae/gal) products, and 39 fl oz/A of 3.7 lbs ae/gal products. This glyphosate rate can only be applied up to the eight-leaf stage of sugarbeet. This rate should be applied to any field with weeds greater than two to three inches in height or with difficult to control species such as wild buckwheat, lambsquarters, and common and giant ragweed.

    Watch for Midge as Wheat Approaches Heading Stage

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    by Phillip Glogoza, Extension Educator - Crops

    There could be about 70% of the region's wheat acres at the heading stage when wheat midge are emerging, based on those acres being planted in the high risk window (Figure 1). Heading is the growth stage when wheat is attractive to female midge for egg laying, and the time the plant is most susceptible to injury from midge larval feeding. Though midge populations have been small in recent years, this will be the most wheat acres we have had that are susceptible to midge in many years.

    Aphids in Small Grains - June 29, 2009

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    by Dr. Ian MacRae, U of MN Extension Entomologist

    There have been some reports of bird cherry-oat aphids (Figure 1 and Figure 2) in small grains in NW and WC MN over the last week. The populations I've seen are at very low numbers. Add to this, the recent rainy weekend will likely have had a significant impact on those aphid populations, but it's still a good idea to scout for aphids in small grains. The most damaging aphid populations are ones that reach threshold around flag leaf stage, if populations are at or near threshold at this time, delaying treatment until heading may cost you yield.

    Bacterial leaf stripe of wheat: Something to keep in mind

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    by Dr. Charla Hollingsworth, U of MN Extension Plant Pathologist

    Bacterial leaf stripe is a disease that can usually be found on wheat in the Red River Valley (RRV) later as crop growth stages progress. The disease (caused by a Xanthomonas sp.) can develop and become severe rapidly after the crop reaches the heading growth stage. Bacterial leaf stripe (BLS) can cause significant yield losses on some varieties. Like other disease issues, development is dependent on weather conditions and the presence of susceptible plant hosts. Epidemics of BLS occurred in the RRV during 2005 and again in 2008.

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